Acheron longus ( Walker, 1853 )

Hassan, Muhammad Asghar & Liu, Xingyue, 2021, Taxonomic notes on owlflies from Pakistan (Neuroptera: Myrmeleontidae Ascalaphinae), Zootaxa 4970 (3), pp. 401-452 : 404-407

Acheron longus ( Walker, 1853)

Ascalaphus longus Walker, 1853: 435 . Type locality: Bangladesh.

Ascalaphus loquax Walker, 1853: 434 . Type locality: Bangladesh.

Ascalaphus anticus Walker, 1853: 434 . Type locality: Bangladesh.

Ascalaphus trux Walker, 1853: 432 . Type locality: Bangladesh.

Helicomitus ctenocerus Gerstaecker, 1894: 101 . Type locality: India (Assam).

Hybris kolthoffi Navás, 1927: 2 . Type locality: China (Jiangsu).

Diagnosis. Acheron longus is characterised by a relatively large body size (forewing length: 39.1 mm) and hyaline or dark wing membrane, which depends upon the maturity of the individual, but it lacks distinct markings. The pterostigma is brownish in both wings, wider than long, with five crossveins, and the apical area beyond Sc+R has three rows of cells. Although the antennae are normal in the female, without serration, the basal flagellomeres in male have distinct lateral spines.

Measurement (♂ n=1). Forewing length: 39.1 mm, width 10.4 mm; hind wing length: 36.1 mm, width 9.4 mm; abdominal length 41.0 mm; body length 51.5 mm.

Re-description. Male ( Fig. 1A ). Head ( Fig. 1B ). Postorbital sclerite and occiput yellow. Vertex flat at distal half, yellow, coronal suture brownish, with mixed long dark brown and greyish yellow setae. Frons yellow, with mixed dark brown and greyish yellow setae. Paraocular band greyish yellow. Clypeus dark brown, slightly brownish yellow at lateral margins, distally with rows of dark brown setae. Labrum dark brown, with stiff dark brown and brownish setae. Mandibles brownish yellow, reddish brown at tip, with black setae at proximal 1/3. Maxillary and labial palpi brownish yellow, with black setae. Posterior genal triangle greyish yellow. Eyes divided by a transverse furrow. Antennal toruli greyish yellow, arise more or less below the transverse furrows of eyes ( Fig. 1H ). Antenna shorter than distance between base of forewing to pterostigma, brownish yellow; scape yellow, anterolaterally dark brown, with mixed dark and greyish yellow setae; pedicel brownish with dark setae; basal flagellomeres with distinct lateral spines. Club brownish, pyriform, with verticils ( Figs 1A–C, G ).

Thorax ( Fig. 1B ). Dorsal cervical plates yellow, with long dark brown and short greyish yellow setae; cervical sclerite yellow. Pronotum broader than long, yellow, medially with a dark brown stripe, lateral and posterolateral margins dark brown, with dark brown setae; anterior- and posterior margins flexed upward, lateral margins rounded. Mesonotum brownish yellow, with a predominant dark brown longitudinal stripe on the median, sub-median and anterolateral margins, with dark brown setae. Metanotum brownish yellow, anterolateral margins of postscutellum narrowly dark brown, with dark brown setae ( Fig. 1B ). Pleuron dark brown, with distinct yellow stripes, transverse on meso- and inclined on metatorax, with greyish yellow and dark brown setae ( Fig. 1D ).

Legs dark brown to brownish yellow ( Fig. 1D ). Foreleg. Coxae brownish with pale yellow setae, posterolaterally with black setae. Trochanter brownish, with short black setae. Femur brownish, anterolaterally brownish yellow, with mixed short and long black setae. Tibia brownish, dorsomedially with a narrow yellow spot, with mixed long and short black setae; tibial spurs reddish brown, equal in length to Ta1–Ta2. Tarsomeres dark brown, Ta5 as long as the combined length of Ta1–Ta4. Pretarsal claws reddish brown. Mid leg. Coxae dark brown, yellow at hind margin, with long greyish yellow setae, hind and lateral margins with dark brown setae. Trochanter brownish, with short black setae. Femur dark brown, setae as in foreleg. Tibia and tibial spurs as in foreleg. Hind leg. Coxae, trochanter, femur and tibia concolorous with mid leg. Tibial spurs equal in length to Ta1. Ta1 is slightly longer than Ta2; Ta2–Ta4 subequal in length; Ta5 is shorter than combined length of Ta1–Ta4.

Wings ( Fig. 2 ). Membrane transparent, subcostal area shaded with light brown. Veins brownish yellow, with sparse short black setae. Pterostigma wider than long, rhomboid-shaped, brownish, with five crossveins, apical area beyond Sc+R with three rows of cells ( Figs 1E–F ). Forewing slightly longer than hind wing. Presectoral area with eight crossveins, with the distal one biaereolated. Rs with seven major forks. Hind wing. Presectoral area with six crossveins, with the distal one biaereolated. Rs with seven major forks.

Abdomen longer than hind wing in male ( Fig. 1A ), shorter in female. Tergum evenly dark brown, with a brownish yellow median stripe. T1 split dorsally, with long dark brown setae. Acrotergite brownish yellow. T2 yellowish brown, lateral margins dark brown, with short black setae. T3 brownish yellow, lateral and hind margins dark brown, proximally with a few short black setae. T4 brownish yellow, lateral and hind margins dark brown, without distinct setae. T4–T8 mostly dark brown, lateral margins distinctly covered with short black setae. Sternum dark brown. S1, proximal half of S2, and proximal 1/3 of S3–S8 brownish yellow, with short black setae.

Male genitalia ( Figs 3A–E ). Brownish yellow. Tergum 9 (T9) oblong, posterolateral margin slightly produced, covered with long black setae; sternum 9 (S9) subquadrate, with triangular apex in ventral view, covered with long black setae; ectoprocts (epr) subquadrate, narrow at distal margin, covered with long black setae; gonarcus (gs) brownish yellow, medially notched, slightly divergent at lateral margins; parameres (pa) brownish, bean-shaped in ventral view, waved-face laterally; pulvini (pv) yellow, with several long yellow gonosetae.

Material examined. PAKISTAN. Balochistan province: 1♂, District Pishin, 26.vi.2006, NIM, leg. Mishkat Ullah ( NIM) .

Distribution. Pakistan (New country record); Bangladesh (Sylhet), Bhutan, China (Fujian, Guangxi, Hainan, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Sichuan, Taiwan, Tibet, Yunnan, Zhejiang), India (Assam, Sikkim, Meghalaya, West Bengal), Malaysia, Myanmar, Japan, Thailand ( Walker 1853; McLachlan 1873a; van der Weele 1909; Fraser 1922; Ghosh & Sen 1977; Ghosh 1988, 2000; Michel 2005; Wang et al. 2018; Yang et al. 2018; Tauber et al. 2019; Oswald 2020).

Figures

FIGURE 1. Acheron longus (Walker). Male. A. Dorsal habitus; B. Head and thorax, dorsal view; C. Antenna; D. Lateral habitus; E–F. Pterostigma of right fore- and hind wing; G. Proximal region of antennae; H. Head, anterior view. Scale bars: 5.0 mm (A, D); 2.0 mm (B); 1.0 mm (H).

FIGURE 2. Acheron longus (Walker). Male. Right fore- and hind wing. Scale bar: 2.0 mm. Abbreviations: C = Costa; Sc = Subcosta; RA = Radius anterior; RP = Radius posterior; MA = Media anterior; MP = Media posterior; CuA = Cubitus anterior; CuP = Cubitus posterior; A = Anal vein; Pt = Pterostigma.

FIGURE 3. Acheron longus (Walker). Male genitalia. A. Lateral view; B. Same, ventral view; C–E. Gonarcus, parameres and pulvinus: C. Dorsal view; D. Same, ventral view; E. Same, lateral view. Scale bar: 0.5 mm. Abbreviations: ect = ectoproct; gs = gonarcus; pa = parameres; pv = pulvinus; T = tergites; S = sternites.